TWENTY-SIXTH SESSION. 
79' 
Prof. Alwood: I have photographs here illustrating the methods I pursue 
in regard to pruning old orchards and I hand them around. The Station or- 
chards had been greatly neglected prior to the organization of the Experi- 
ment Station and we have followed the custom in them of severe pruning 
with the very best results. In fact, I always advise a thorough pruning of 
neglected orchards. Yet I do not wish to be understood to mean indiscrim- 
inate cutting or chopping away of limbs. I think it of the greatest impor- 
tance to judiciously open the tops of old trees and thus stimulate growth, but 
at the same time I realize that, carried too far it would be a shock instead 
of a benefit. 
Mr. Kellogg: This is very true, but I believe that the main cause of lack 
of potency in pollen is exhaustion through overbearing, which is corrected by 
proper pruning. 
Prof. Alwood: Do you mean that the pollen has lost its potency, or that 
the tree has lost its constitutional vigor? 
Mr. Kellogg: The potency of the pollen is lost through the loss of consti 
tutional vigor. 
Prof. Alwood: Yes; I believe that too; it is exactly what I have said. 
Professor John Craig of the Iowa Agricultural College and Experiment Sta- 
tion presented the following paper: 
SOME EFFECTS OF THE FREEZE OF 1898-9 IN IOWA. 
BY PROF. JOHN CRAIG, IOWA AGRICULTURAL COLLEGE, AMES, IA. 
Undoubtedly a certain amount of root-killing occurs every year in some 
part of the country. Whenever on light soils the ground is found bare of 
vegetation or snow covering during hard freezing weather, injury of this 
kind may occur. Hartig * suggests that this injury received by the roots 
while the tops remain unhurt is due to the thinner periderm of the roots as 
well as to their relatively more extended period of activity. If weather 
conditions have been such as to produce complete vegetative inactivity then 
root injury on the accession of severe freezing might not be expected to the 
same extent as when soil and climate conditions of the autumn favor root 
growth. These environmental conditions, of course, may determine in a 
measure the extent of the injury, but if the frost is very severe and the sur- 
face of the ground unprotected, root-killing is certain to ensue. In other 
words, w r hen the ground is bare and the frost severe, situation and variet; 
of stock within certain limits have little influence upon the results. Injury 
is, however, usually most -severe where the subsoil is of a hard and impervious 
character and overlaid by a thin layer of upper -soil. 
In early spring the appearance of the root-killed tree is not sufficiently 
marked to. enable an observer to distinguish it from the uninjured specimen.. 
The twigs and branches retain their plumpness until the commencement 
of the vegetative process. The flower buds open, and in some instances 
fruit sets; the leaves partially expand. At this stage the trees begin to 
give indications of an abnormal condition; growth ceases; the blossoms and 
embryo fruits wither and fall, soon to be followed by the leaves. Some- 
times an entire tree top dies with the exception of a branch or two. If the 
*Diseases of Trees, p. 289. 
